凸面对焊钢制管法兰 meaning in Chinese

steel pipe welding neck flanges with raised face for pn 0mpa
steel pipe welding neck flanges with raised face for pn 25mpa
steel pipe welding neck flanges with raised face for pn 5mpa
steel pipe welding neck flanges with raised face for pn 6mpa (bar)gb/t 8-pn 0mpa(bar)